Instrument board light



1937- J. M. ROPER INSTRUMENT BOARD LIGHT I Filed Aug. 13, 1956 INVENTOR wk M Roper 64. a M

ATTORNEY Patented Aug. 10, 1937 UNITED STATES PATENT OFFICE 2 Claims.

(Granted under the act of March 3, 1883, as

amended April 30, 1928: 370 0. G. 757) This invention relates to an instrument board light and has for an object to provide an im-' proved lighting arrangement especially applicable to the lighting of the instrument board and cockpit of an airplane, and at the same time the lighting of a chart board located in the center of the cockpit. A further object of this invention is to provide a non-reflecting instrument board lighting arrangement which will be non-glaring and hence make the instruments easier to read and also which will not reflect any image of the instrument board to the adjacent windshield.

A further object of this invention is to provide l5 a light fixture that may be mounted to direct a light on the instrument board and at the same time have a controllable shutter for directing a light ray into the cockpit onto a chart board located therein.

2 With the foregoing and other objects in view,

the invention consists in the construction, combination and arrangement of parts, as will be described more fully hereafter.

In the drawing:

2 Fig. 1 is an elevational' view of a board with the instrument lights of this invention mounted in operative position along the sides of the cockpit of an airplane;

Fig. 2 is an elevational view of the-instrument light fixture, per se;

Fig. 3 is a sectional view through Fig. 2, and

Fig. 4 is a section on line 4-4 of Fig. 3.

There is shown at) the cockpit of an airplane having a chart board located at H and the 35 customary instrument board located at- 62, the pilot seat being located as at i3. Secured along the opposite sides I4 of the cockpit ill is a bracket l5 having a threaded clamp bolt l6 mounted for universal adjustment therein by means of the ball-nut W and socket nut it which clamp on opposite sides of a hemisphere so formed in the bracket l5 and having a slot 22 through which the clamp bolt it extends.

The clamp bolt 86 is provided with a clamp eye 2i through which extends a socket 22, the

socket 22 being preferably of the type described in my companion case Serial No. 94,182, filed August 4, 1936. This socket includes stranded conducting wires 23 extending through the cable 2d and flange 3| against which a compression spring 32 is located, the other end of the compression spring 32 resting against the inside of the inturned flange 29 to thus yieldably urge the conductor terminal 26 against the lamp contact 33 in the base 34 of a lamp 35, the lamp base 34 being provided with pins 36 for yieldably holding it in bayonet slots 31 formed in the socket 22. The electric socket described forms the subject matter of and is claimed in the copending application above referred to.

Mounted on the outside of the socket 22 is cylindrical sleeve 38 which is of such a diameter that it will snugly fit thereabout. This sleeve 38 is provided with a depressed neck 39 which acts as a base for. lens 40, which is held in position therein by a split ring 4| fitting into an internal groove 42. the form of a Nicol prism so that the light rays 43 passing therethrough will be polarized. The Nicol prism is mounted for axial rotation to adjust the relative plane of polarization. A plurality of oblong slots 44 in the side of the sleeve 38 permit light rays 46 to pass therethrough from the lamp 35. A shutter sleeve 41 and a cooperating slot 49, and a, handle flange 48 for positioning the same provide a means for shutting off or permitting the light to fall upon the chart board, while allowing the light rays 43 to reach the instrument board continuously.

I It has been found that utilizing a Nicol prism, as at 40, substantially reduces reflection or glare from the instruments on the instrument board l2, and at the same time prevents reflections of the instrument board on the windshield. 50. The plane of polarization is rotated until the reflection isat a minimum, thus making it easier for the pilot to read his instruments more accurately without being bothered by reflection or glare in his eyes. At the same time by utilizing the control flange d8 of the shutter 41 he controls the amount of light reaching the chart board when the same is needed and 'may cut it off entirely when it is not needed without interfering, with the use of the light on the instrument board and without the necessity of using additional lighting means therefor.

Other modifications and changes in the proportions and amangements of the parts may be made by those skilled in the art without departing from the nature and scope of the invention, as defined in the appended claims.

The invention described herein may be manuiactured and used by or for the Government of the United States of America for governmental This lens 40 is preferably in- 10 shutter means for directing and cutting off other light rays from the same lamp in the lighting fixture to the cockpit, said first mentioned light directing means including a Nicol prism for polarizing the light rays to the instrument board, said Nicol prism being rotatable on the lens axis.

2. In a light fixture for a cockpit and instrument board of an airplane, means for universal- 1y mounting the light fixture to the side of the cockpit, means for directing light rays from the lamp in the light fixture to the instrument board, and shutter means for directing and cutting off other light rays from the same lamp in the lighting fixture to the cockpit, said first mentioned light directing means including a Nicol prism for polarizing the light rays to the instrument board.

JOHN M. ROPER. 

